At the moment users with 1080p (or 1440p) displays gain no visual quality from a Stadia Pro subscription.
There is a workaround to force delivery of a 4K stream to such users (which is then downscaled by Chrome to their native resolution).
However this is a terrible way to achieve increased visual quality due to the increased server load of rendering the source at 4K, and the inefficiency of downscaling a highly compressed 4K stream.
It'd make much more sense for Stadia to give Pro users a bitrate allotment for their stream; they'd then be able to choose how to apportion said allotment, either on higher resolutions, higher bitrates, or neither (if their connection cannot sustain the increased bandwidth requirements).
I completely agree. There is literally no excuse for having the options for 1080p and 4k but not 1440p, other than straight up laziness/incompetent design.
I got a 1440p Monitor because I literally a forum post from June when they actually did have the option to click 1440p, only to learn AFTER I get my monitor that they, for some dumb reason, got rid of it.
Bizarre and infuriating. This platform is so close to being good, but it's like they actively work to make sure it's never living up to it's potential.
For 1440p, have you tried the Stadia+ chrome extension?
Install it -> go to the stadia website -> shift+tab to bring up the right-hand stadia overlay -> Stadia+ button -> force resolution -> 1440p
It's obviously unofficial, and I'm not sure precisely how it achieves said resolution, but worth a try.